Anal fistula surgery

Expert reviewer, Mr Stephen Pollard, Consultant General Surgeon, May 2017
Next review due May 2020

An anal fistula is a tunnel that develops between the skin around your anus and the inside of your back passage (anal canal). Anal fistula surgery is an operation to close this tunnel.

You will meet the surgeon carrying out your procedure to talk about your care. It might be different to what we’ve described here because it will be designed to meet your individual needs.

Older man smiling

About anal fistula

An anal fistula can develop after you’ve had an infection in or around your anus, such as an abscess (a collection of pus). One in three people with an abscess in their anus will go on to develop a fistula. It can also be caused by long-term bowel conditions, such as Crohn's disease.

The external opening of a fistula is on the skin near to your anus. The internal opening of a fistula can be in your anal canal, or your rectum. Your rectum is where stools are stored just before they leave your body through your anal canal.

A fistula is usually a simple tunnel between your skin and your anal canal. However, it can sometimes be more complex and have a network of tunnels, or it can pass through the muscles of your anal canal. This can make it more difficult to treat.

Symptoms and diagnosis of anal fistula

Symptoms of an anal fistula can include:

  • pus or blood coming from your anal area
  • pain, discomfort and swelling in and around your anus
  • red, itchy and broken skin around your anus
  • a visible opening close to your anus

These symptoms aren't always caused by an anal fistula but if you have them, see your GP.

Your GP may be able to diagnose an anal fistula by examining your back passage using a gloved finger. If you have a fistula, or if your GP isn’t sure whether you have a fistula, you may be referred to a specialist to have further tests. These may include:

A proctoscopy is a procedure to look at the inside of your anal canal by inserting a short instrument into your anus to hold it open so that the specialist can look at the lining. A flexible sigmoidoscopy is a procedure using a thin, flexible tube with a camera in it to look further inside your bowel. This is put inside your back passage; images are sent to a TV screen, so your doctor can see if there is a fistula.

Deciding on anal fistula surgery

This information is intended to help you understand the pros and cons of having anal fistula surgery. Think about how important each issue is to you, and then talk to your doctor. You and your doctor can work together to decide what's right for you. Your decision will be based on your doctor’s expert opinion and your personal values and preferences.


  • The procedure is usually done as a day-case, so you probably won’t need to stay in hospital overnight.
  • The operation can help the fistula to heal fully and prevent any further infection.


  • After your operation, your wound may not heal well enough, and you may need another operation.
  • There is a small chance you may develop complications after the operation, including being incontinent of faeces (stools).
  • You may have some pain immediately after your operation, and it can be uncomfortable to open your bowels.

Preparing for anal fistula surgery

Your surgeon will explain how to prepare for your anal fistula surgery. For example, if you smoke you will be asked to stop, as smoking increases your risk of getting a wound or chest infection, which can slow your recovery, and it also slows wound healing

Your operation will be done under general anaesthesia which means you’ll be asleep during the operation. It can also be done with a spinal anaesthetic, which means you’ll be awake during the operation, but the lower part of your body will be numb. After your operation, you will usually be able to go home the same day.

A general anaesthetic can make you sick so it's important that you don't eat or drink anything for six hours before your procedure. Follow your anaesthetist/doctor's advice and if you have any questions, just ask.

Your surgeon will discuss with you what will happen before, during and after your operation, and any pain you might have. If you’re unsure about anything, ask. No question is too small. Being fully informed can help set your mind at ease and will allow you to give your consent for the procedure to go ahead. You may be asked to do this by signing a consent form.

You may be asked to wear compression stockings to help prevent blood clots forming in the veins in your legs. You may need to have an injection of an anticlotting medicine called heparin, as well as or instead of wearing compression stockings.

What are the alternatives to anal fistula repair?

Surgery is the usual treatment for anal fistulas as it is the most likely treatment to help your fistula heal properly.

If you have Crohn’s Disease and an anal fistula, it’s important to have your condition well controlled using medicines, before you have any surgery.

What happens during anal fistula surgery?

The aim of any operation to fix an anal fistula is to close the tunnel(s) from your bowel to your skin, and to leave your bowels working as well as possible. There isn’t one operation that can fix all types of fistula. So, which operation you have will depend on the type of fistula you have and where it is.

Your surgeon will talk with you about the different choices available, the risks and benefits and why they are recommending a particular operation for you. If your fistula isn’t too deep, your surgeon will suggest a fistulotomy to close it. For straightforward fistulas, this type of operation works well. The fistula is opened up so that it can heal from the inside out. The wound is left open without any stitches.

There are other types of treatment that can be used to repair an anal fistula, such as special glue or plugs. However, there is not yet enough evidence to say whether these treatments work well enough for everyone.

What to expect afterwards

After the operation, you’ll need to rest until the effects of the anaesthetic have passed. You will likely have some discomfort as the anaesthetic wears off. But you'll be offered pain relief as you need it. You can begin to drink and eat when you feel ready.

You’re likely to have a small amount of bleeding after your operation. If you’re bleeding a lot, or the bleeding is getting worse, speak to your doctor.

You will be given a date for a follow-up appointment with your surgeon.

Make sure someone can take you home. And ask someone to stay with you for a day or so while the anaesthetic wears off.

Recovering from anal fistula surgery

You will likely feel sore after having anal fistula surgery. You can take over-the-counter painkillers such as paracetamol or ibuprofen if you need pain relief. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.

Having a general anaesthetic can really take it out of you. You might find that you're not so co-ordinated or that it's difficult to think clearly. This should pass within 24 hours. In the meantime, don't drive, drink alcohol, operate machinery or sign anything important.

Your wound should heal within six weeks. You’ll be asked to keep the wound clean and dry to help it heal well. If your wound is bleeding or there is any fluid coming from it, you can also use a dressing or gauze pad over the wound. You might find it helpful to use a sanitary pad to protect your clothes.

Have warm baths each day (called sitz baths). These can help to ease pain and discomfort as well as keeping your wound clean. Don’t add anything to the bath water as this can irritate your wound.

It can be uncomfortable the first time you open your bowels after the operation. Taking a painkiller around 20 minutes before going to the toilet may help. You may be given a laxative medicine, which will help to keep your stool soft so that it’s less painful to go to the toilet.

Your surgeon will give you advice about driving, going back to work, having sex and getting back to your usual activities and routine.

Possible side-effects of anal fistula surgery

Side-effects are the unwanted but mostly temporary effects you may get after having the procedure.

The main side-effect of having anal fistula surgery is that it may be painful or uncomfortable for a time after the procedure. You might also find it uncomfortable to open your bowels after the operation. You can take painkillers to manage any pain.

Possible complications of anal fistula surgery

All medical procedures come with some risk. But how these risks apply to you will be different to how they apply to others. Be sure to ask for more information if you have any concerns.

Complications are when problems occur during or after the operation. Specific complications of anal fistula operation include the following.

  • Bleeding.
  • Becoming incontinent of faeces (stools). This is when you can’t control going to the toilet and you may soil yourself.
  • Your wound takes a long time to heal.
  • Problems opening your bowels (constipation or impaction, which is severe constipation).
  • Problems passing urine (urinary retention).
  • The fistula may come back.
  • Narrowing of your anal canal. This is the short tube that connects your rectum with your anus. If this becomes narrow, it can make it more difficult for you to open your bowels.

Frequently asked questions

  • An anal fissure is a tear or an ulcer that develops in the lining of your anus. There is usually no obvious cause of an anal fissure, though sometimes passing a hard stool can cause one to develop. The treatment for a fissure is to keep the area clean, take painkillers and make sure that your stools are soft and easy to pass. This means drinking enough fluid and eating fruit, vegetables and foods that have fibre in them. Doing this gives the fissure a chance to heal without other treatment.

    An anal fistula is a tunnel that connects the skin near your anus to your rectum. It usually develops after an infection. Treatment for anal fistula involves having an operation.

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Related information

    • Fistula in ano. Medscape., updated September 2015
    • Anorectal disorders. Oxford handbook of colorectal surgery (online). Oxford Medicine Online., published October 2011
    • Anorectal abscess. PatientPlus., last checked June 2014
    • Anal fistulas and fissures. Medscape., updated December 2016
    • Evaluation of anorectal disorders. MSD Manuals., last full review October 2016
    • Simpson JA, Banerjea A, Scholefield JH. Management of anal fistula. BMJ 2012; 345:e6705 doi:10.1136/bmj.e6705
    • Flexible sigmoidoscopy. Medscape., last updated February 2016
    • Anal abscess and fistula. Association of Coloproctology of Great Britain and Ireland., accessed 22 February 2017
    • Venous thromboembolism: reducing the risk for patients in hospital. National Institute for Health and Care Excellence (NICE), 2015.
    • Vogel JD, Johnson EK, Morris AM, et al. Clinical practice guideline for the management of anorectal abscess, fistula-in-ano, and rectovaginal fistula. Dis Colon Rectum 2016; 59:1117–33. doi:10.1097/DCR.0000000000000733
    • Recovering after your anal fistula operation. Guys and St Thomas’ NHS Foundation Trust., published April 2014
    • Anal fissure. NICE Clinical Knowledge Summaries., last revised July 2016
  • Reviewed by Alice Rossiter, Specialist Health Editor, Bupa Health Content Team, May 2017
    Expert reviewer, Mr Stephen Pollard, Consultant General Surgeon, May 2017
    Next review due May 2020

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